std::vec: Remove the function same_length

The basic construct x.len() == y.len() is just as simple.

This function used to be a precondition (not sure about the
terminology), so it had to be a function. This is not relevant any more.

src/librustc/middle/typeck/infer/combine.rs

@@ -88,7 +88,7 @@ pub trait Combine {
         // future we could allow type parameters to declare a
         // variance.
 
-        if vec::same_length(as_, bs) {
+        if as_.len() == bs.len() {
             result::fold_(as_.iter().zip(bs.iter())
                           .map(|(a, b)| eq_tys(self, *a, *b)))
                 .then(|| Ok(as_.to_owned()))
@@ -419,7 +419,7 @@ pub fn super_fn_sigs<C:Combine>(
     this: &C, a: &ty::FnSig, b: &ty::FnSig) -> cres<ty::FnSig> {
 
     fn argvecs<C:Combine>(this: &C, a_args: &[ty::t], b_args: &[ty::t]) -> cres<~[ty::t]> {
-        if vec::same_length(a_args, b_args) {
+        if a_args.len() == b_args.len() {
             result::collect(a_args.iter().zip(b_args.iter())
                             .map(|(a, b)| this.args(*a, *b)))
         } else {

src/libstd/vec.rs

@@ -123,11 +123,6 @@ use unstable::raw::{Box, Repr, Slice, Vec};
 use vec;
 use util;
 
-/// Returns true if two vectors have the same length
-pub fn same_length<T, U>(xs: &[T], ys: &[U]) -> bool {
-    xs.len() == ys.len()
-}
-
 /**
  * Creates and initializes an owned vector.
  *